A source with knowledge of an investigation of the killings says 78 elephants have been poisoned in the country this month.
The elephants were found in the remote Sinamatella area of Hwange National Park on Monday, Zimbabwe national park officials say. The park received international attention in July as the site where American dentist Walter Palmer shot and killed Cecil the lion.
Officials say rangers recovered 35 tusks, and poachers escaped with three. They said the remaining elephants were too young and their tusks had not fully developed.
The recent cyanide poisonings are not the first in Zimbabwe, where the poison is common and is often stolen from gold mines. In 2013, around 300 elephants were killed with cyanide in Hwange National Park in a single incident.
Cyanide is one of the most rapidly acting of all known poisons, preventing cells of the body from using oxygen, essentially suffocating the animal.
"It's a poacher's dream," said a chemical expert who spoke to CNN, noting that it is cheap, highly effective and silent, compared with other methods.
"Poachers know that the moment they pull a trigger, it is easier for us to find them," said Caroline Washaya-Moyo, a spokeswoman for the Zimbabwe Parks and Wildlife Management Authority. "So they use cyanide."
But while cyanide may be silent, it is also an indiscriminate killer, affecting other wildlife and contaminating the ecosystem. The contamination increases with rain.
"We need to go quickly and decontaminate the area," Washaya-Moyo said. "The rainy season is coming, so we need to move with speed."
Just days before this week's latest poaching incident, authorities at Harare International Airport seized 173 kilograms (381 pounds) of ivory headed for Singapore.